Method of making seamless tubes.



G. H. BLAXTBR.

METHOD OF MAKING SEAMLESS TUBES.

APPLICATION FILED APR. 8, 1911.

1,076,545, Patented Oct. 21, 1913.

WITNESSES T 0 all whom, it ntay concern:

rrE sTA'rEs PA GEORGE H. BLAXTEB. 0F BEAVER FALLS, PENNSYLVAI VIA. I

METHOD OF MAKING SEAMLESS TUBES.

Be itknown that I, GEORGE H. BLAXTER.

.a resident of Beaver Falls, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Methods of Making Seamless Tubes, of

which the following is a specification.

This invention relates to a method of making seamless tubing, and its object is to provide a method of making finished tubing by a rolling process, or in other wordsmak ing a hotfinished seamless tube.

Generally stated the invention consists in first rolling a hot hollow blank over a plug or ball between grooved rolls, and preferably simultaneously therewith forcing it onto a mandrel-bar, then rolling the same on a mandrel bar in'one or more stands of groovedi 'olls, and finally reeling or cross {)olling said tube, preferably on a mandrel In the accompanying drawing Figure 1 is a diagrammatic view of the arrangement. of apparatus for carrying out the method; Fig. 2 is a detail view illustrating the first step of the operation. or the plug rolling; Fig. 3 is a detail view illustrating the second step of the operation, or the rolling on a mandrel in a grooved mill; and Fig. 4.- is a detail view illustrating the third step in the operation, that is reeling or cross rolling the tube on the mandrel.

In carrying out the method I start with a. hollow blank 1, which may be either pierced on an ordinary piercin mill, or produced by casting, the former being preferred. This hollow blank is suitably heated before subof mandrel 5, the blank preferably being forced between the rolls by a suitable pusher, such" as indicated a t'6. The mandrel bar '5 is preferably of such a nature that the tubecan be finished thereon, although this is not necessary as the ball or plug. may be-s upported between the rolls 3 by any usual mandrel bar. As shown the bar 5 is of comparatively large diameter, having the terminal ball or plug 4. The rear endof the mandrel bar 5 is supported against "a gate or stop 9 which receives the force of the impact during the process of forcing the blank Specification of LettersPatent. Application--filed April 8, 1911. Serial No. 619,726.

. Patented @ct. 231; 19113..

1 over the ball or plug between the rolls 3,

after which operation the ball or plug readily falls away from the mandrel. The effect of this operation, is that the blank is reduced andelongat ed and cleared of all scale inside and out. If desired the blank may be given a plurality of passes through a plug mill, the mandrel bar for the last'pass preferably being adapted to serve as an interior mandrel for the subsequent steps of the process. Preferably, however, only one or two passes in the plug mill are given, while the blank is still quite hot and ductile, so that the liability of interior scores'or scratches being produced by the plug is reduced to a minimum.

From the plug mill the partly reduced tube, while supported on the mandrel bar 5, passes to a grooved mill comprising one or more stands of grooved rolls 11, preferably located alternately in horizontal and vertical planes as shown, whereby the tube is subsures first on top and bottom and then on the two lateral sides. It will be understood that any number of pairs or stands of such rolls may be employed,- and that their position with relation to each other may be varied as desired. They need not be arranged alternately with the axes at right angles, but instead the blank may be given a quarter turn between passes. The effect of these grooved rolls is to further compress the walls of the tube upon the mandrel bar, giving it the required uniform thickness throughout and giving it a smooth and substantially polished surface inside and out. Preferably the tube will leave the grooved mill of substantially the desired length and diameter and thickness of wall of the finished tube.

From the grooved mill the tube, while preferably still 'on the mandrel bar, passes to the cross rolling or reeling mill 13, there preferably being provided between said mills a feed table or trough 14: of slightly greater length than the tube and mandrel.

bar, so that by the time the forward end of the tube enters the cross rolls it is entirely free from the continuous mill and is therefore free to rotate as it must under the ac tion of the cross rolls.

On the exit side of the cross rolls is a similar trough or table sizing rolls if necessary or desired. The action of the reeler or cross rolls is to further smoothen and true the tube interiorly and exteriorly if not already smoothened sufiiciently in the grooved mill.

According to the method described it is possible to finish a seamless tubeat the initial heat of the billet. When the operation starts with a solid billet it must be heated for piercing, and this heat will be sufficient. with the proper handling to enable the tube to be reduced to its final or finished form. All of the operations take place very rapidly, and except when giving a plurality of passes through the plug mill, the blank travels continuously forward with little or no interruption through the entire process. The effect of the plug rolling is to rapidly reduce the blank and clear the same both interiorly and exteriorly of scale, so that itpasses onto the mandrel bar with practi- 'cally clean surfaces so that in the subsethe same ma'ndrel bar or over an ordinary drum head mandrel, serves to true the tube and reduce the gage to that finally desired and makes the tube perfectly circular exteriorly and straightens the same. The tube as it comes from the cross rolls is practially in finished form, but if desired may be sized and afterward cold drawn for highly finished product.

With this invention the output of the mill is very large and the cost of production much lower than with the processes usually employed, and the tube produced is so perfect as to dispense entirely with cold drawing, and even forhighly finished work where cold drawing is desired, the number of cold drawing passes can be materially reduced on account of the practically smooth and perfect contour both interiorly and exteriorly of'the tube. v y

' The several mills illustrated may be of any suitable ty es, so long as they perform the functions or which they are severally intended.

What I claim is: 1. The method of manufacturing seamless tubing, which consists in rolling a hollow blank in a plug mill to reduce and elongate the same and free the same from scale, then rolling the same on a traveling bar in a grooved mill to further reduce the same to uniform thickness and smooth the same interiorly and exteriorly, and finally cross rolling or reeling the same to true and further smooth the same.

2. The method of manufacturingseam less tubing, which consists in rolling a hollow blank in a plug mill. to reduce and elongate the same and .free the same from. scale, then rolling the same in a grooved mill on a mandrel bar traveling with the blank through said mill to'further reduce the? same to uniform wall thickness and produce a smooth interior surface for the tube,

unifmrm wall thickness and smooth the same interiorly and exteriorly, and finally cross rolling or reeling the same While on said mandrel bar to true and further smooth the same.

4. The method of mamifacturing seamless tubing, which consists in rolling a hollow blank in a. continuous mill and on a mandrel bar traveling with the blank through said mill to reduce and elongate the same to substantially finished gage and length and without the production of interior scores or ridges, and then cross rolling or reeling the same while on said mandrel bar to true and further smooth the same. a

5. The method of manufacturing seamless tubing, which consists in forcing a heated tubular blank between reducing means over and onto a mandrel bar, and then reducing the tube between said bar and outside reducing means. thereby preventing the formation of interior scores or ridges and finally cross rolling or reeling the tube while on said mandrel bar. i

In testimony whereof, I have hereunto set my hand.

GEORGE H. BLAXTER. Vitnessesr A O. A. Ronnnmc, MARY E. CAHooN.

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